微机继电保护测试仪中高性能数字信号发生器的研究与实现

介绍了基于高性能数字信号处理器(DSP)芯片TMS320F2812实现直接数字频率合成器的设计思想、工作原理和软硬件体系结构。提出一种优化的直接数字频率合成(DDFS)实现方法,改进的方法之一是将离散正弦表初始化到内部高速RAM中运行;之二是将浮点数用Q格式的定点数代替,将浮点数的乘除运算转化为定点的乘法和移位计算。试验和实际证明该方法可进一步提高数字信号发生器的实时性与稳定性。

Research and realization of high performance digital signal generator in microcomputer protection tester

The design concept,the operational principle,the software and hardware structure of the DDFS(Direct Digital Frequency Synthesizer) based on the high performance DSP (Digital Signal Processor) TMS 320F 2812 are introduced,with an optimized approach to it. One of improvements is to download the discrete sine table in the internal RAM(Random Access Memory) during initialization for real time operation;the other is to apply fixed point numbers in Q15 format instead of floating point numbers for changing multiply and division operations of floating point numbers into multiply and shift operations of fixed point numbers. Experiments prove that the real time performance and stability of digital signal generator are enhanced.